The present invention relates to an improvement in a process for treating an effluent gas by irradiation with a form of radiation. More particularly, t he present invention pertains to an improvement in the desulfurizing and denitrating efficiency in a process for purifying an effluent gas in which desulfurization and denitration are mainly effected by utilizing both addition of ammonia and irradiation with a form of radiation
The term "desulfurization" is employed in this specification to mean removal of sulfur oxides (generally abbreviated to "SO.sub.x " contained in effluent gases in various forms, while the term "denitration" means removal of nitrogen oxides (generally abbreviated to "NO.sub.x ") also contained in effluent gases in various forms. A large volume of combustion gases is ceaselessly generated by factories and electric power plants every day. These effluent gases contain at least either one of SO.sub.x and NO.sub.x, without exception, although the actual SO.sub.x or NO.sub.x content depends on the kind of effluent gas. SO.sub.x and NO.sub.x are usually contained in effluent gases as harmful gas components. Accordingly, it is essential to desulfurize and denitrate effluent gases before they are released into the atmosphere in order to prevent air pollution.
A variety of desulfurizing and denitrating processes have heretofore been proposed and put into practical use. However, many of them are wet processes which use a large amount of water or a specific chemical substance, and therefore it is necessary to treat a large amount of the waste water and slurry generated as by-products, which represents another difficult problem. In particular, treatment of an effluent gas having a relatively high content of harmful gas components produces an exceedingly large amount of waste water and slurry, so that it is difficult to treat them. Thus, the prior art effluent gas treating techniques are not necessarily satisfactory.